Peristaltic pump

Abstract

A peristaltic pump includes a cam shaft, first and second pinch-valve cams, first and second pinch-valve cam followers, a plunger cam, a plunger-cam follower, a tube receiver, a spring-cam plunger, a position sensor, and a processor. The plunger cam is coupled to the cam shaft. The plunger-cam follower is configured to engage the plunger cam. The spring-biased plunger is coupled to the plunger-cam follower where expansion of the plunger cam along a radial angle intersecting the plunger-cam follower as the cam shaft rotates pushes the plunger cam to disengage the spring-biased plunger from the tube and a spring coupled to the spring-biased plunger biases the spring-biased plunger to apply the crushing force to the tube. The position sensor is operatively coupled to the spring-biased plunger and is configured to determine a position of the spring-biased plunger. The processor estimates fluid flow using the position.

What is claimed is: 
     
       1. A peristaltic pump, comprising:
 a cam shaft; 
 first and second pinch-valve cams coupled to the cam shaft; 
 a first pinch valve cam follower configured to engage the first pinch-valve cam; 
 a second pinch valve cam follower configured to engage the second pinch-valve cam; 
 a plunger cam coupled to the cam shaft; 
 a plunger-cam follower configured to engage the plunger cam; 
 a tube receiver configured to receive a tube; 
 a spring configured to provide a bias; 
 a plunger biased by the spring, the plunger coupled to the plunger-cam follower, wherein expansion of the plunger cam along a radial angle intersecting the plunger-cam follower as the cam shaft rotates actuates the plunger away from the tube; 
 a position sensor operatively coupled to the plunger configured to determine a position of the plunger; and 
 a processor coupled to the position sensor, wherein the processor is configured to estimate fluid flow of fluid within the tube utilizing the position. 
 
     
     
       2. The peristaltic pump according to  claim 1 , further comprising an angle sensor operatively coupled to the cam shaft configured to determine an angle of rotation of the cam shaft. 
     
     
       3. The peristaltic pump according to  claim 1 , wherein the processor compares a first static region of the position sensor to a second static region of the position sensor to estimate the fluid flow. 
     
     
       4. The peristaltic pump according to  claim 3 , wherein the processor determines the first static region by identifying the first static region within a predetermined range of angles as indicated by an angle sensor. 
     
     
       5. The peristaltic pump according to  claim 4 , wherein the processor determines the second static region by identifying the second static region within a second predetermined range of angles as indicated by the angle sensor. 
     
     
       6. The peristaltic pump according to  claim 4 , wherein the processor determines the first and second static regions by measuring the position of the plunger as determined by the position sensor at predetermined angles as indicated by the angle sensor. 
     
     
       7. The peristaltic pump according to  claim 1 , wherein the processor compares a first static region measured by the position sensor to a second static region measured by the position sensor to estimate the fluid flow. 
     
     
       8. The peristaltic pump according to  claim 6 , wherein the processor determines the first static region by identifying a peak movement of the plunger as measured by the position sensor and identifies the second static region to be after the identified peak movement. 
     
     
       9. The peristaltic pump according to  claim 6 , wherein the processor determines the second static region by identifying an end of the first static region. 
     
     
       10. The peristaltic pump according to  claim 1 , further comprising an electric motor operatively coupled to the cam shaft to apply a rotational torque to the cam shaft. 
     
     
       11. The peristaltic pump according to  claim 10 , wherein the electric motor is at least one of a stepper motor, a DC motor, a brushless DC motor, a brushed DC motor, an AC motor, a polyphase induction motor, an electric motor with at least one permanent magnet coupled to a stator or a rotor, and an induction motor. 
     
     
       12. A peristaltic pump, comprising:
 a housing; 
 a motor; 
 a cam shaft operatively coupled to the motor such that rotation of the motor rotates the cam shaft; 
 a plunger cam coupled to the cam shaft for rotation therewith; 
 a pivot shaft operatively coupled to the housing; 
 a plunger pivotally coupled to the pivot shaft, the plunger having a cam follower configured to engage the plunger cam of the cam shaft, wherein the plunger is configured to pivot to a first position to compress a tube and to a second position away from the tube; 
 a bias member configured to bias the plunger to the first position to compress the tube; 
 a position sensor coupled to the plunger to measure a position of the plunger; and 
 a processor coupled to the position sensor to estimate a volume of fluid discharged from the tube when the bias member causes the plunger to move towards the first position, wherein:
 the plunger and the plunger cam are configured to compress the tube using only a force of the bias member, 
 the plunger cam is configured to only retract the plunger to the second position, and 
 the plunger is configured to engage the plunger cam such that the plunger cam does not force the plunger against the tube. 
 
 
     
     
       13. The peristaltic pump according to  claim 12 , wherein the plunger is U-shaped.